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Router showing modem at 100 Mbps suddenly

sneak

Occasional Visitor
Everything was fine and I had a loud sound outside due to lightning, my UPS shut off along with everything connected to it (including modem and router). My 2.5 GbE PCIE wasn't showing up in Windows after turning everything on. I pulled it out and observed visible damage on the back of the PCB. My router port 4 also doesn't work anymore. I can't seem to get my router to stop showing my modem's port speed as 100 Mbps, and it's heavily crimping my speeds.


Here is the gear:
  • Hitron CODA56
  • ASUS RT-BE86U (Merlin 3006.102.3)
  • Cat6 cables
  • TERRAMASTER F4 424-Pro
  • ASRock X570 Taichi

Originally I was using LAN 1 for my work PC but right now I don't have a work PC and should receive a new one tomorrow, so I have an ethernet cable hanging out of LAN 1 not connected to anything. LAN 2 has a cable connected to my NAS (prior to LAN 4 on the router breaking I was using LACP with ports 1 and 2 on the NAS but I've disabled all that and I'm just using 1 cable now). LAN 3 has my computer connected to it.

Router page shows LAN port 1 as inactive as well as port 4, since port 4 has nothing connected and port 1 has a cable only connected on the router side. Nothing wrong with that.

Router shows LAN port 2 as "2.5 Gbps" when hovering, which is correct as it's connected to the NAS. LAN port 3 shows "1 Gbps", which is correct as it's connected to my PC motherboard, which doesn't support 2.5. The issue comes with the router reporting the "10G WAN/LAN 1" as "100 Mbps". It has marked it yellow. This was the issue I had in the past, but it was with the LAN ports and a different cable resolved it. I have tried 4 cables and cannot get this thing to read properly. I've tried power cycling the modem, and the router. There is also some information (see attached file) provided by the router.

I called my ISP to see if they're doing something weird after getting people's connections restored today and they told me they see something weird with the signal since yesterday. I wasn't having issues yesterday. They're sending someone out tomorrow..
 

Attachments

  • vIV0eM6.png
    vIV0eM6.png
    24 KB · Views: 7
If everything connected to this port (modem or router side) shows 100Mbps only - it got damaged. What usually damages is the transformers behind the port. Depending on what pair was damaged - you get 100Mbps or nothing.
 
It is the WAN port so the only thing connected is the modem. I don't have any other modems to connect to it.

I guess my only options are to connect the modem directly to my PC and see if it still shows 100 Mbps. If it does the modem is faulty, if it doesn't the router is faulty?
 
Last edited:
Don’t change the default font colour. Your colour choice makes the text hard to read on Default and Light forum styles.

This connection has two ends. If your cable is good - it’s most likely one of the two LAN ports involved. In some cases both ports may have suffered damage.
 
Don’t change the default font colour. Your colour choice makes the text hard to read on Default and Light forum styles.
I didn't change anything. Not sure what you're seeing, but it looks normal to me.

EDIT: I switched site to light mode and see it. I didn't change it but I figure it's something to do with the forum software used. When I was trying to post the reply the internet randomly went out and I noticed the modem was rebooting. Not sure what happened with that, but I had copied what I already tried to reply with and pasted it once the internet went back up. The forum probably did that on it's own. I edited the text back to normal.
 
Back to the point ... I agree with @Tech9 that either the router's WAN port or the modem's local port is partially fried. Maybe both :(. Your ISP's service person will be able to test the modem, and hopefully will replace it if bad, so just wait for that visit. If your luck is bad you will be looking at having to replace the router. I am a little bit optimistic that it might be the modem, since the ISP say they can see something is wrong; but that's not certain.
 
Back to the point ... I agree with @Tech9 that either the router's WAN port or the modem's local port is partially fried. Maybe both :(. Your ISP's service person will be able to test the modem, and hopefully will replace it if bad, so just wait for that visit. If your luck is bad you will be looking at having to replace the router. I am a little bit optimistic that it might be the modem, since the ISP say they can see something is wrong; but that's not certain.
Thanks. They're not going to replace it as it's my own. But that's a good point that they should be able to test it and make sure it can switch to the right mode.
 

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